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Derivative of \( \displaystyle 5 x \left(25 x^{2} - 45 x + 27\right) \)

Problem 2.1419 · hard

Differentiate \( \displaystyle f(x) = 5 x \left(25 x^{2} - 45 x + 27\right) \).
  1. \[ \frac{d}{d x} 5 x \left(25 x^{2} - 45 x + 27\right) \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} \left(125 x^{3} - 225 x^{2} + 135 x\right) \]
    algebraDistribute 5*x into the parentheses.✓ Proved
  3. \[ = \frac{d}{d x} 135 x - \frac{d}{d x} 225 x^{2} + \frac{d}{d x} 125 x^{3} \]
    sumApply the sum rule for differentiation.✓ Proved
  4. \[ = 135 \frac{d}{d x} x - 225 \frac{d}{d x} x^{2} + 125 \frac{d}{d x} x^{3} \]
    constant-multiplePull out the constant coefficients.✓ Proved
  5. \[ = 375 x^{2} - 450 x + 135 \]
    power simplifyApply the power rule to each term. Multiply the constants to get the final result.✓ Proved
Answer \( 15 \left(5 x - 3\right)^{2} \)

Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. The reviewers disagree about how one step is explained; every verdict is in the receipt.

The full receipt
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: fail (error) — Step 1 claims to start the differentiation but does not apply the product rule; the derivative of a product must be expanded before the subsequent algebraic steps. The solution skips a required rule application, making the first step incorrect.
  • qwen3.6:27b-mlx: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-10-03
  • gpt-oss:20b: fail (error) 2026-10-03 — Step 1 claims to start the differentiation but does not apply the product rule; the derivative of a product must be expanded before the subsequent algebraic steps. The solution skips a required rule application, making the first step incorrect.
  • qwen3.6:27b-mlx: pass 2026-10-03
  • gpt-oss:20b: pass 2026-10-03

Proved: SymPy reduced the difference between the two sides to zero. Checked independently: a separate method, named above, confirmed it. Checked numerically: the two sides agree at every sampled point, which is evidence, not proof. Reviewed: a model or a person read it; that is all a sentence can have. Solution by gemma4:26b, checked 2026-10-03 with SymPy 1.14.0.